updating countryCode comment to: country ISO 3166-1 alpha-2 uppercased code
Adding info on where to find types of citations produced by PMC citation ingestmodule
fixing comment
introducing address field
adding new countryCode field to affiliation
#577 updating Citation namespace
#577 introducing common.citations.Citation schema
removing redundant ReferenceBasicMetadata and ReferenceMetadata definitions which are also available in standalone avdl definitions, replacing definitions with import statements.
removing deprecated PersonWithInferencedData avro schema
removing deprecated DocumentWithInferencedData and DataSetReferenceWithInferencedData avro schemas
#568 renaming Citations#sourceDocumentId field to Citations#documentId
#568 introducing CitationEntry and Citations schemas
rename a field